Rattlesnake

We start the day at a MODERATE hazard, but expect to see conditions deteriorate with ongoing snowfall and wind transport. Human triggered avalanches involving the new snow will become increasingly likely as the day progresses. Below the new snow, well-defined weak layers exist in the upper 1-3 feet of the snowpack. Slides breaking on these layers will be large, wide, and destructive. At low and middle elevations, the snowpack is warm from days of heat and now wet from rain. Small wet snow avalanches will be easy to trigger on steep slopes and will quickly gain mass and speed on large slopes. It is a bit of a mess out there. Safe travel today will require you to avoid rain-soaked snow down low, dodge the wind slabs up high, and manage a widespread persistent slab problem.

THE WET, THE DRY, and THE UGLY

In recent days, the snow has settled into a conditional stability, following an intense storm, a major wind event, and a widespread avalanche cycle last week. A set of weak layers buried 1-3 feet below the snow surface gradually became less reactive this week, and lots of folks were poking into steeper terrain and not triggering slides. Unfortunately, we are firmly headed in the other direction today.

THE WET: At the low elevations, you'll find mostly puddles and mud. If your day starts here, you'll struggle to keep your sled cool and your skins dry while grimacing about all the rocks you're riding over. Cimb a bit, and you'll encounter a saturated snowpack, melted by days of heat and now soaked with rain. Small wet snow avalanches will be easy to trigger on steep slopes where the snow is wet. 

THE DRY: In upper elevation terrain, you'll find a dry, still wintery snowpack. In the last 18 hours, the mountains picked up a fresh 5-10 inches of dense snow. Moderate winds are building slabs with this fresh snow as you read this. Ongoing snowfall and wind will help these slabs become larger, more reactive, and more destructive as the day progresses.

THE UGLY: As a careful reader, you likely noticed that the persistent slab problem is still at the top of the list, despite the more likely wind and wet problems. That's because these layers are the ones that will make very large, surprising, and hard-to-predict avalanches. There is a good deal of uncertainty about how these will respond to the new load being applied to them. In sheltered terrain, its less likely that the recent snow will wake these layers back up. In windy terrain where slabs are building, the chances of these weak layers failing are greater. In the middle elevations, where these weak layers have been soaked by rain, all bets are off. These persistent weak layers are our primary problem because they are the main driver of terrain selection today. Dodging wind slabs and wet snow problems will not eliminate your chance of encountering one of these beasts.

If this all sounds complex, I'm doing a good job describing it. Go out into the snowy/rainy world prepared to encounter a different snowpack than you've been playing on in recent days. If you choose to enter avalanche terrain, manage the uncertainty involving the persistent slab problem (dry up high, wet down low) by choosing simpler, gentler terrain where the consequences of being caught and carried in a slide are less. As a friendly reminder, you can always enjoy a lower-stress day of turns and throttle by steering clear of avalanche terrain and terrain threatened from above.